Many photoresist strippers and residue removers have been proposed for use in the microelectronics field as downstream or back end of the manufacturing-line cleaners. In the manufacturing process a thin film of photoresist is deposited on a wafer substrate, and then circuit design is imaged on the thin film. Following baking, the unpolymerized resist is removed with a photoresist developer. The resulting image is then transferred to the underlying material, which is generally a dielectric or metal, by way of reactive plasma etch gases or chemical etchant solutions. The etch gases or chemical etchant solutions selectively attack the photoresist-unprotected area of the substrate.
Additionally, following the termination of the etching step, the resist mask must be removed from the protected area of the wafer so that the final finishing operation can take place. This can be accomplished in a plasma ashing step by the use of suitable plasma ashing gases or wet chemical strippers. Finding a suitable cleaning composition for removal of this resist mask material without adversely affecting, e.g., corroding, dissolving or dulling, the metal circuitry has also proven problematic.
As microelectronic fabrication integration levels have increased and patterned microelectonic device dimensions have decreased towards the size of atoms, the heat formed as current passes through the circuits has become a serious problem. It has become increasingly common in the art to employ copper metallizations as the conductor material, instead of aluminum, since copper is more beneficial in reducing the heat formation. These copper containing microelectronic materials have presented additional challenges to find acceptable cleaner compositions. Many process technology compositions that have been previously developed for “traditional” or “conventional” semiconductor devices containing Al/SiO2 or Al (Cu)/SiO2 structures cannot be employed with copper metallized structures. For example, hydroxylamine based stripper or residue remover compositions are successfully used for cleaning devices with Al metallizations, but are practically unsuitable for those with copper metallizations. Similarly, many stripper or residue remover compositions used for cleaning devices with copper metallizations are not suitable for Al metallized devices unless significant adjustments in the compositions are made.
Removal of these etch and/or ash residues following the plasma etch and/or ashing process for such copper and aluminum metallized microelectronic structures has proved problematic, particularly for substrates metallized with copper. Failure to completely remove or neutralize these residues can result in the absorption of moisture and the formation of undesirable materials that can cause corrosion to the metal structures. The circuitry materials are corroded by the undesirable materials and produce discontinuances in the circuitry wiring and undesirable increases in electrical resistance.
Heretofore, photoresist strippers have often contained amines since they generally show superior cleaning performance in attacking hardened photoresist and in the ability to strip such hardened photoresist from the surface of the microelectronic substrates. However, copper is generally also severely attacked by amines and significant metal corrosion can occur if such a conventional photoresist stripper is utilized without modification. Therefore, it is highly desirable to provide a copper compatible photoresist stripper or cleaner for use in the microelectronics industry, particularly for copper metallized materials. It is also highly desirable to provide a copper compatible photoresist stripper or cleaner for use in the microelectronics industry, particularly for copper metallized materials, that is also compatible for use with aluminum metallized materials. Since the same shift in technology from aluminum to copper metallization is being seen in the development of flat panel displays, it is also desirable to provide a stripper/cleaner that can be use in producing such flat panel displays.